fossil

Ammonite Fossil

Subclass Ammonoidea

Hardness 3.5-4 (calcite), various shades of grey, white, and brown, vitreous to dull luster, planispiral shell structure.

Identified October 24, 2026More fossil →

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Physical properties

Hardness 3.5-4 (calcite), various shades of grey, white, and brown, vitreous to dull luster, planispiral shell structure.

Formed through permineralization of marine mollusk shells in ancient shallow seas during the Mesozoic Era.

Used extensively as index fossils in geology, educational specimens, decorative display items, and jewelry.

Ammonites are cephalopods closely related to modern nautiluses and octopuses, becoming extinct alongside the dinosaurs 66 million years ago.

Easily identified by their distinctive coiled, chambered shells; found worldwide in marine sedimentary rock layers.

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image